border-1px($color){
    position:relative;
    &:after{
        display: block;
        position: absolute;
        left: 0;
        bottom: 0;
        width: 100%;
        border-top: 1px solid $color;
        content: ' ';
        margin-bottom:0.3rem;
    }
}
bg-image($url){
    background-image: url($url + '@2x.png')
    @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3){
        background-image: url($url + '@3x.png')
    }
}    